The Einstein equivalence principle (EEP) underpins all metric theories of gravity. One of its key aspects is the local position invariance of nongravitational experiments, which is captured by the gravitational redshift. The iconic gravitational redshift experiment places two fermionic systems, used as clocks, in different gravitational potentials and compares them using the electromagnetic field. However, the electromagnetic field itself can be used as a clock, by comparing the phases acquired by two optical pulses propagating through different gravitational potentials. A fundamental point in the implementation of a space-based large-distance optical interferometric experiment is the suppression of the first-order Doppler effect, which dominates the weak gravitational signal necessary to test the EEP. Here, we propose a novel scheme to suppress it by subtracting the phase-shifts measured in a one-way and two-way configuration between a ground station and a satellite. We present a detailed analysis of this technique within the post-Newtonian framework and perform simulations of its performance using realistic satellite orbits and state-of-the-art fiber technology at the telecom wavelength of 1550 nm.

General relativity predicts that black holes are described by the Kerr metric, which has integrable geodesics. This property is crucial to produce accurate waveforms from extreme-mass-ratio inspirals. Astrophysical environments, modifications of gravity, and new fundamental fields may lead to nonintegrable geodesics, inducing chaotic effects. We study geodesics around self-interacting rotating boson stars and find robust evidence of nonintegrability and chaos. We identify islands of stability around resonant orbits, where the orbital radial and polar oscillation frequency ratios, known as rotation numbers, remain constant throughout the island. These islands are generically present in both the exterior and the interior of compact boson stars. A monotonicity change of rotation curves takes place as orbits travel from the exterior to the interior of the star. Therefore, configurations with neutron-star-like compactness can support degenerate resonant islands. This anomaly is reported here for the first time, and it is not present in black holes. Such configurations can also support extremely prolonged resonant islands that span from the exterior to the interior of the star and are shielded by thick chaotic layers. We adiabatically evolve inspirals using approximated post-Newtonian fluxes and find time-dependent plateaus in the rotation curves which are associated with island-crossing orbits. Crossings of external islands give rise to typical gravitational-wave glitches found in non-Kerr objects. Furthermore, when an inspiral is traversing an internal island that is surrounded by a thick chaotic layer, a new type of simultaneous multifrequency glitch occurs that may be detectable with space interferometers such as the Laser Interferometer Space Antenna and can serve as evidence of an extreme-mass-ratio inspiral around a supermassive boson star.

As a fundamental parameter for modern cosmology, the Hubble constant $H_0$ is experiencing a serious crisis. In this paper, we explore an independent approach to measure $H_0$ based on the time-delay cosmography with strong gravitational lensing of a quasar by a galaxy cluster. Specifically we focus on the strong lensing system SDSS $\mathrm{J}1004+4112$ with the maximum image separation of ${14.62}^{\prime \prime }$, the first system of a quasar lensed by a galaxy cluster with five multiple images. Incorporating the latest time-delay measurements, we investigate the lens model dependence from the combination of 16 different lens mass models. We find that the lens model dependence is indeed large, with the combined measurement of the Hubble constant of $H_0={67.5}_{-8.9}^{+14.5}\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$ that is obtained by summing posteriors of the Hubble constant from the 16 models with equal weighting. Interestingly, our results show that the value of Hubble constant decreases as the complexity of the perturbation around the lens increases, although weighting based on positional errors of quasar images does not significantly improve the $H_0$ constraint. We find that the 16 different mass models predict largely different shapes of the lensed quasar host galaxy as well as other lensed galaxies behind the cluster. By selecting two mass models that best reproduces those shapes, the constraint on the Hubble constant is significantly tightened to $H_0={59.1}_{-3.5}^{+3.6}\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$. While we caution that our analysis still does not fully explore all the possible mass model uncertainty, our results highlight the importance of including as many constraints as possible such as extended shapes of lensed galaxies for obtaining tight constraints on the Hubble constant from cluster-lensed quasar lens systems.

We investigate possible traces of the nuclear symmetry energy slope ($L$) in the gravitational wave emission of neutron stars. For fixed stellar mass values, we examine how the slope influences the stellar radius, compactness, the tidal deformability, the frequency of the quadrupole fundamental fluid mode, and the damping time of the mode due to the gravitational wave emission. We demonstrate that all these physical quantities are sensitive to the slope and could potentially impose significant constraints on it.

Supergravity theories with nonminimal Kähler potentials are characterized by a nontrivial field space manifold with corresponding nontrivial kinetic terms. The scattering amplitudes in these theories can be calculated at fixed background field values by making a field redefinition to Riemann normal coordinates. Because of the Kähler structure of supergravity, a more compact method for calculating amplitudes is obtained by a redefinition to Kähler normal coordinates. We compare both methods and calculate the explicit transformations and amplitudes for several examples in the context of no-scale supergravity with one and two chiral superfields. We show that in all cases the equivalence of the scattering amplitudes using either Riemann normal or Kähler normal coordinates is possible only at extremal points of the scalar potential.

The electromagnetic and gravitational form factors of ${\mathrm{\Omega }}^{-}$, a spin-$3/2$ hyperon composed of three $s$ quarks, are calculated by using a covariant quark-diquark approach. The model parameters are determined by fitting to the form factors of the lattice QCD calculations. Our obtained electromagnetic radii, magnetic moment, and electric-quadrupole moment are in agreement with the experimental measurements and some other model calculations. Furthermore, the mass and spin distributions of ${\mathrm{\Omega }}^{-}$ from the gravitational form factors are also displayed. It is found that the mass radius is smaller than its electromagnetic ones. Finally, the interpretations of the energy density and momentum current distribution are also discussed.

In the $U(1{)}_X$ extension of the minimal supersymmetric standard model, there are three Higgs singlets and the corresponding trilinear terms in the Higgs effective potential. These new terms can allow a strongly first-order electroweak phase transition (EWPT) for a wide parameter space. We use codes cosmotransitions to analyze the thermal evolution of the Higgs effective potential and calculate nucleation temperature. To find reasonable parameter spaces for strongly first-order EWPT, we randomly scan many parameters, which is numerically expensive. The diagrams are shown, that can lead to the 125 GeV Higgs mass and satisfy the first-order EWPT. This work benefits the phenomenology of $U(1{)}_X$ SSM and exploring new physics beyond the SM.

We study the potential of Weinberg’s ${\mathbb{Z}}_2\times {\mathbb{Z}}_2$-symmetric three-Higgs-doublet model. The potential is designed to accommodate $CP$ violation in the scalar sector within a gauge theory, while at the same time allowing for natural flavor conservation. This framework allows for both explicit and spontaneous $CP$ violation. $CP$ can be explicitly violated when the coefficients of the potential are taken to be complex. With coefficients chosen to be real, $CP$ can be spontaneously violated via complex vacuum expectation values (VEVs). In the absence of the terms leading to the possibility of $CP$ violation, either explicit or induced by complex VEVs, the potential has two global $U(1)$ symmetries. In this case, spontaneous symmetry breaking would, in general, give rise to massless states. In a realistic implementation, those terms must be included, thus preventing the existence of Goldstone bosons. A scan over parameters, imposing the existence of a neutral state at 125 GeV that is nearly $CP$ even shows that, in the absence of fine-tuning, the scalar spectrum contains one or two states with masses below 125 GeV that have a significant $CP$-odd component. These light states would have a low production rate via the Bjorken process and could thus have escaped detection at the Large Electron-Positron Collider. At the LHC, the situation is less clear. While we do not here aim for a full phenomenological study of the light states, we point out that the $\gamma \gamma$ decay channel would be challenging to measure because of suppressed couplings to $WW$.

The idea that new physics could take the form of feebly interacting particles (FIPs)—particles with a mass below the electroweak scale, but which may have evaded detection due to their tiny couplings or very long lifetime—has gained a lot of traction in the last decade, and numerous experiments have been proposed to search for such particles. It is important, and now very timely, to consistently compare the potential of these experiments for exploring the parameter space of various well-motivated FIPs. The present paper addresses this pressing issue by presenting an open-source tool to estimate the sensitivity of many experiments—located at Fermilab or the CERN’s SPS, LHC, and FCC-hh—to various models of FIPs in a unified way: the Mathematica-based code senscalc.

Sampling topological quantities in the Monte Carlo simulation of lattice gauge theory becomes challenging as we approach the continuum limit ($a\to 0$) of the theory. In this work, we introduce a conditional normalizing flow model to sample $U(1)$ gauge theory in two dimensions, aiming to mitigate the impact of topological freezing when dealing with smaller values of the $U(1)$ bare coupling. To train the conditional flow model, we utilize samples generated by hybrid Monte Carlo method, ensuring that the autocorrelation in topological quantities remains low. Subsequently, we employ the trained model to extrapolate the coupling parameter to values where training was not performed. We thoroughly examine the quality of the model in this region and generate uncorrelated samples, significantly reducing the occurrence of topological freezing. Furthermore, we propose a retrainable approach that utilizes the model’s own samples to enhance the generalization capability of the conditional model. This method enables sampling for coupling values far beyond the initial training region, expanding the model’s applicability.

We determine ${\alpha }_{\mathrm{s}}$, $m_c$, and $m_b$ using the relativistic quarkonium sum rule and the renormalization group summed perturbation theory. Theoretical uncertainties, especially originating from the variation of the renormalization scale, are considerably reduced for the higher moments. Our determinations using the renormalization group summed perturbation theory are also found to be stable with respect to the use of $\overline{\mathrm{MS}}$ quark mass for the condensate terms. We obtain ${\alpha }_s^{(n_f=5)}(M_z)=0.1171(7)$, ${\overline{m}}_c=1281.1(3.8)\mathrm{MeV}$, and ${\overline{m}}_b=4174.3(9.5)\mathrm{MeV}$.

We study the behavior of a hadronic matter in the presence of an external magnetic field within the van der Waals hadron resonance gas model, considering both attractive and repulsive interactions among the hadrons. Various thermodynamic quantities like pressure ($P$), energy density ($ϵ$), magnetization ($\mathcal{M}$), entropy density ($s$), squared speed of sound ($c_{\mathrm{s}}^2$), and specific-heat capacity at constant volume ($c_v$) are calculated as functions of temperature ($T$) and static finite magnetic field ($eB$). We also consider the effect of baryochemical potential (${\mu }_B$) on the above-mentioned thermodynamic observables in the presence of a magnetic field. Further, we estimate the magnetic susceptibility (${\chi }_{\mathrm{M}}^2$), relative permeability (${\mu }_{\mathrm{r}}$), and electrical susceptibility (${\chi }_{\mathrm{Q}}^2$) which can help us to understand the system better. Through this model, we quantify a liquid-gas phase transition in the $T-eB-{\mu }_B$ phase space.

The Dalitz decays of the positive-parity $D_{sJ}^{(*)}$ charmed mesons, $D_{sJ}^{(*)}\to D_s^{(*)}{\ell }^{+}{\ell }^{-}$ with $J=0$, 1, 2 and $\ell =e$, $\mu$, are important processes to investigate the nature of the $D_{sJ}^{(*)}$ states. We analyze the full set of decays, considering the four lightest $D_{sJ}^{(*)}$ mesons as belonging to the heavy quark spin doublets $s_{\ell }^P={\frac{1}{2}}^{+}$ and ${\frac{3}{2}}^{+}$, with $s_{\ell }^P$ the spin parity of the light degrees of freedom in mesons. The description implies relations among the observables in various modes. We study the decay distributions in the dilepton invariant mass squared and the distributions in the angle between the charged lepton momentum and the momentum of the produced meson, which are expressed in terms of universal form factors and of effective strong couplings. Such measurements are feasible at present facilities.

In this work, we study the linear stability of superfluid phases of matter irrespective of the nature of microscopic degrees of freedom and the strength of interactions between them. Famously, assuming invariance under Galilean boosts and a phonon-roton single-particle dispersion relation, Landau predicted superfluid helium 4 would become unstable for large enough superfluid velocities. Here, we demonstrate that such instabilities generically follow from a change of sign of one of the eigenvalues of the matrix of second derivatives of the free energy. Our only assumption is the existence of static thermodynamic equilibrium, irrespective of any invariance under boosts or microscopic statistics. Turning on dissipation, we show that a linear dynamical instability also develops, leading to exponential growth in time of perturbations around equilibrium. Specializing to Galilean superfluids and assuming the existence of bosonic quasiparticles, our criterion reproduces Landau’s critical velocity for Bose-Einstein condensates. Our criterion also reduces to the well-known maximal supercurrent in weakly coupled superconductors described either by Landau-Ginzburg or Bardeen-Cooper-Schrieffer theory. Further, it correctly reproduces the onset of the instability in relativistic, strongly coupled superfluids without quasiparticles at zero as well as finite temperature, which we construct using gauge/gravity duality. As a less trivial application of our criterion, we show that in dirty superfluids the instability manifests itself first in the thermal diffusion mode instead of the superfluid sound mode. Our work provides a simple, comprehensive, and unified description of the large superflow instability of superfluids and superconductors at any temperature independent of the microscopic details of the system and the strength of interactions.

We discuss the influence of various contributions of the ${\mathrm{\Lambda }}_c{\overline{\mathrm{\Lambda }}}_c$ potential on the energy dependence of the cross section $e^{+}{e}^{-}\to {\mathrm{\Lambda }}_c{\overline{\mathrm{\Lambda }}}_c$ near the threshold. New BESIII experimental data on the cross section and electromagnetic form factors $G_E$ and $G_M$ are taken into account. Our predictions are in good agreement with experimental data. We predict a bound state of ${\mathrm{\Lambda }}_c{\overline{\mathrm{\Lambda }}}_c$ at energy $\sim 38\mathrm{MeV}$ below the threshold that may manifest itself in anomalous behavior of light meson production cross sections in a given energy region.

A number of nuclear decay anomalies have been reported in the literature, which purport to show periodic variations in the decay rates of certain radioisotopes. If these reports reflect reality, they would necessitate a seismic shift in our understanding of fundamental physics. We provide the first mechanism to explain these findings, via the misalignment mechanism of QCD axion dark matter, wherein oscillations of the effective $\theta$ angle induce periodic variation in nuclear binding energies and hence decay rates. As we expect this effect to be most pronounced in low-$Q$ systems, we analyze 12 years of tritium decay data ($Q\simeq 18.6\mathrm{keV}$) taken at the European Commission’s Joint Research Centre. Finding no statistically significant excess, we exclude axion decay constants below $9.4\times {10}^{12}–1.8\times {10}^{10}\mathrm{GeV}$ (95% confidence level) for masses in the $1.7\times {10}^{-23}–8.7\times {10}^{-21}\mathrm{eV}$ range.

We study how quantum systems can harvest entanglement from the quantum degrees of freedom of the gravitational field. Concretely, we describe in detail the interaction of nonrelativistic quantum systems with linearized quantum gravity, and explore how two spacelike separated probes can harvest entanglement from the gravitational field in this context. We provide estimates for the harvested entanglement for realistic probes which can be experimentally relevant in the future, since entanglement harvesting experiments can provide evidence for the existence of quantum degrees of freedom of gravity.

The renormalization group flow of a Hermitian field theory is shown to have trajectories which lead to a non-Hermitian parity-time ($\mathcal{P}\mathcal{T}$) symmetric field theory for an axion coupled to a fermion in spacetime dimensions $D=4-\epsilon$, where $\epsilon >0$. In this renormalizable field theory, the Dirac fermion field has a Yukawa coupling $g$ to a pseudoscalar (axion) field and there is quartic pseudoscalar self-coupling $u$. The robustness of this finding is established by considering flows between $\epsilon$ dependent Wilson-Fisher fixed points and also by working to three loops in the Yukawa coupling and to two loops in the quartic scalar coupling. The flows in the neighborhood of the nontrivial fixed points are calculated using perturbative analysis, together with the $\epsilon$ expansion. The global flow pattern indicates flows from positive $u$ to negative $u$; there are no flows between real and imaginary $g$. Using summation techniques we demonstrate a possible nonperturbative $\mathcal{P}\mathcal{T}$-symmetric saddle point for $D=3$.

We investigate thermodynamics of static and spherically symmetric black holes (BHs) in the Horndeski theories. Because of the presence of the higher-derivative interactions and the nonminimal derivative couplings of the scalar field, the standard Wald entropy formula may not be directly applicable. Hence, following the original formulation by Iyer and Wald, we obtain the differentials of the BH entropy and the total mass of the system in the Horndeski theories, which lead to the first law of thermodynamics via the conservation of the Hamiltonian. Our formulation covers the case of the static and spherically symmetric BH solutions with the static scalar field and those with the linearly time-dependent scalar field in the shift-symmetric Horndeski theories. We then apply our results to explicit BH solutions in the Horndeski theories. In the case of the conventional scalar-tensor theories and the Einstein-scalar-Gauss-Bonnet theories, we recover the BH entropy obtained by the Wald entropy formula. In the shift-symmetric theories, in the case of the BH solutions with the static scalar field, we show that the BH entropy follows the ordinary area law even in the presence of the nontrivial profile of the scalar field. On the other hand, in the case of the BH solutions where the scalar field linearly depends on time, i.e., the stealth Schwarzschild and Schwarzschild-(anti–)de Sitter (AdS) solutions, the BH entropy also depends on the profile of the scalar field. By use of the entropy, we find that there exists some range of the parameters in which a Schwarzschild-AdS BH with nontrivial scalar field is more thermodynamically stable than a Schwarzschild-(AdS) BH without scalar field in general relativity. Finally, we consider the Horndeski theories minimally coupled to the $U(1)$-invariant vector field, where BH solutions contain the mass and the electric charge, and clarify the conditions under which the differential of the BH entropy is integrable in spite of the presence of the two independent charges.

We study the scattering of axially incident massless scalar waves by a charged and rotating black hole solution from heterotic string theory called the Kerr-Sen black hole. We compute the scattering cross section using the partial wave approach, for arbitrary incident wavelengths. We compare our results with those of the general relativistic version of a charged and rotating black hole, namely the Kerr-Newman black hole. We present a selection of numerical results showing that these compact objects have similar scattering properties.